The prior art (Japanese Pat. Nos. 671,727 and 755,474) comprises putting a mending cloth on a basic cloth to be mended, stamping out the basic cloth and the mending cloth together with a trimming die, fitting a fitting cloth made from the stamped out portion of the mending cloth into the hole which was previously stamped out, putting a thermoplastic synthetic resin film on the back of the fitting portion, and then heating said thermoplastic synthetic resin film surface through cellophane paper with an iron. The thermoplastic synthetic resin film is fused by heat-pressing with an iron. One part of the resin penetrates into the construction of the basic and mending cloths via gaps between fibers and the other part pentetrates through the gap between the basic cloth and the fitting cloth at the fitting portion. Thus, the basic and mending cloths are adhered strongly by fusion of the synthetic resin film. However, fused thermoplastic synthetic resin sometimes penetrates through the basic and mending cloths and oozes out of the surface. In such case, the appearance of the basic and mending cloths is remarkably spoiled and their texture becomes hard decreasing the practical value of the invention.